Peripheral Artery Disease

As we age and our bad habits and neglect catches up with us, our arteries can start to narrow because of plaque and calcium build-up. When the vessels that supply blood to our arms and legs become narrowed, and blood decrease to these areas, we call this peripheral artery disease. This usually refers to the lower legs, resulting in symptoms of claudication.

Intermittent claudication is a symptom of ischemia, or insufficient blood supply. This is evident when our legs hurt with exertion, but that pain is relieved by rest. Activity demands more oxygen from our blood so when we are active and we feel pain, this is indication there may not be sufficient blood flow particularly when rest relieves this discomfort. Often what people experience with PAD is a crampy, achey sensation in their calf, thigh, or buttock muscle. When you walk, do you get to a point or intensity in which your legs start to really hurt?

Critical limb ischemia is the end-stage of PAD. When we can't even get enough blood to our limbs for them to function normally while at rest, then the feet hurt all the time, even at rest. Wounds don't heal. Our toes lack that vibrant pink color, turning a more darker, cyanotic shade and potentially even gangrene. This is when we risk losing our limbs. Acute limb ischemia can also occur, abruptly, such as when a thrombus or clot blocks the arterial supply to one of our limbs. This is not much different than a thrombus blocking a cardiac artery, in a myocardial infarction, or heart attack.

Ischemia is inadequate oxygen, while necrosis is death of tissue. Gangrene specifically refers to the death of tissue due to inadequate blood supply.

Atherosclerosis

Athero means "porridge-like" and sclerosis means "hardening." Atherosclerosis then refers to athermas or fatty deposits in the artery walls which then causes hardening or stiffening in the blood vessel walls. Atherosclerosis effects the medium and large walled vessels. It is caused by chronic inflammation and activation of the immune system in the artery wall.

Lipids, or fats, are deposited in the blood vessel wall, followed by atheromatous plagues. These plagues cause stiffening of the blood vessel walls which leads to hypertension or raised blood pressure and strain on the heart, while it tries to pump blood against increased resistance.

The plagues also cause stenosis, leading to reduced blood flow, such as in the case of angina. And this can lead to plague rupture, which can create a thrombus, that can block a distant vessel causing ischemia such as with an acute coronary syndrome.

What Can You Do About Your Risk?

There are some risks you can't really modify. Older age is a risk, as is family history. Men are also at increased risk. However, smoking cigarettes or cigars does increase one's risk so you can talk to your primary provider about a cessation program. Alcohol as well, increases risk for atherosclerosis. A poor diet, high in sugar and transfat, is also a significant contributor. You need a healthy amount of fruits and vegetables, as well as healthy fats. Many with atherosclerosis have a very sedentary lifestyle and get little exercise. Poor sleep is another significant, and modifiable risk, as is obesity. Of course, stress plays a role - much more than most appreciate.

If you have diabetes, high blood pressure, chronic kidney disease, inflammatory conditions such as Rheumatoid Arthritis, or anti-psychotic medications, then these are also associated with high risk. If you suffer with intermittent claudication - pain in your legs while exercising that is relieved by rest, then this is of great concern.

When is Atherosclerosis Getting Pretty Severe?

Angina is an end-stage result of atherosclerosis, so is myocardial infarction. Mini-strokes or TIAs (Transient Ischemic Attacks) and strokes, Peripheral Artery Disease and Chronic Mesenteric Ischemia are as well. These diagnosis indicate there is profound damage to your cardiovascular system, and unfortunately, like diabetes, this has been ongoing for years, even decades. Clinicians aren't typically looking for early warnings. They don't have time. Their training is to diagnose disease and prescribe, not optimize wellness.

Let's Look Closer at Intermittent Claudication

Peripheral Artery Disease presents with intermittent claudication. You'll typically feel a crampy feeling in your legs after walking a certain distance. After stopping and resting, the pain will disappear. This most often occurs in the calves, the thighs and buttocks.

Critical Limb Iscemia

Critical limb ischemia can be remembered with a mnemonic using "6 Ps": pain, pallor, pulseless, paralysis, paraesthesia, and perishingly cold. This typically causes a burning pain, and this pain can be worse at night time when the legs are raised up on the bed, as gravity no longer helps pull blood into the foot.

Leriche Syndrome

This syndrome is the result of a blood clot in the distal aorta, or proximal common iliac artery. There is a triad of thigh and buttock claudication, absent femoral arteries, and male impotence. If you are experiencing these symptoms connect urgently with your primary care provider and ask them about Leriche Syndrome.

What Are Clinicians Looking for in their Clinical Exams?

History is super important, but we are also looking for tar staining on the fingers which may indicate a history of smoking. We are also looking for xanthomata, or the yellow fatty deposits typically on the eye lids, indicative of high cholesterol. We are also looking for signs of existing cardiovascular disease such as missing limbs or fingers, after a previous amputations due to critical ischemia. A scar on the chest may be indicative of a previous coronary artery bypass graft. A scar on the inner calf would indicate saphenous vein harvesting, which may also indicate a previous artery bypass graft. We would also look for focal weakness which could indicate previous stroke.

When evaluating pulses on the legs (or peripheries) may be weak or absent. Palpable pulses throughout the body are the radial, brachial, carotid, abdominal aorta, femoral artery, and popliteal, as well as the posterior tibial and dorsalis pedis. A handheld doppler can be used to accurate evaluate the pulses when they are difficult to palpate.

The signs of arterial disease on inspection are skin pallor, cyanosis, dependent rubor which is when the limb is a deep red color when it is lower than the rest of the body, muscle wasting, hair loss, ulcers, poor wound healing, and gangrene. On examination, there may be reduced skin temperature, reduced sensation to the skin, a prolonged capillary refill time of more than 2 seconds, and changes during the Buerger's test.

The Buerger's test is used to test for PAD in the leg. There are two parts to this test. The first part requires the practitioner lay the patient down on their back (supine) and then they will lift one leg about 45 degrees. As they hold them in this position, for one to two minutes, they are looking for pallor in the leg. If it goes pale, then we know that the arterial supply is not sufficient enough to overcome gravity suggesting PAD. Buerger's Angle refers to the angle required to induce pallor because of insufficient blood supply. For example, it could be 30% or less. The second part to this test, is to sit the patient up and hang their legs over the side of the bed or chair. As their legs dangle, blood will return to the legs, assisted by gravity. In a healthy patient, legs will remain pink, but in a patient with PAD, the legs will go blue initially as the ischemic tissue deoxygenates the blood. Then it will turn dark red, after a short time, due to vasodilation in response to the waste products of anaerobic respiration. The dark red color is referred to as rubor.

Let's Look at Leg Ulcers

When our legs fail to get a healthy, oxygenated blood supply, our wounds will be slow to heal, if at all. There is a difference though, between those related to arterial blood supply and those which we refer to as venous ulcers. Arterial ulcers are those related to ischemia related to inadequate blood supply. Typically these are smaller than venous ulcers, deeper with well-defined borders, which gives them a "punched-out appearance" and they occur more periphery, such as in the toes. They also have reduced bleeding and are painful.

Venous ulcers are related to impaired drainage and pooling of blood in the legs. These more often happen after a minor injury to the leg and they are larger, more superficial, and have an irregular, gently sloping border. They affect the gaiter area of the leg, which is the mid-calf area, to the ankle. They are less painful than arterial ulcers and there are often other signs of chronic venous insufficiency such as hemosiderin staining (dark brown discoloration of the skin) and venous eczema.

Clinical Exam for Diagnosing Peripheral Artery Disease

Not only is the history and initial physical exam important for diagnosing peripheral artery disease, but your clinician will also gather data to support their initial findings, such as the ankle-brachial pressure index (ABPI) or use a duplex ultrasound, which measures the speed and volume of blood flow. They may also use an angiography, which may use CT or MRI, with contrast to highlight arterial circulation.

The ABPI is the ratio of the systolic blood pressure, in the ankle around the lower calf, compared to the systolic blood pressure in the arm. These readings are taken manually using a dopler proble. If the arm sysolic reading is 100 and the ankle is 80, then the ratio is 0.8 or 80/100. This can help your clinician indicate the severity of the peripheral arterial disease. A result of 0.9 to 1.3 is normal. However, 0.6 to 0.9 indicates mild PAD, 0.3 to 0.6 is moderate to severe, and a ratio less than 0.3 is severe to critical ischemia. When the results are higher than 1.3, this can indicate calcification of the arteries, making them difficult to compress. This is more common in diabetic patients.

Management of Intermittent Claudication

There are modifiable risk factors, as discussed. Stopping smoking is vital. However, optimal treatment of any co-morbidities is also critical, such as management of hypertension and diabetes. Additionally, one can utilize exercise training involving a structured and supervised program that utilizes walking to near-maximal claudication, then resting, and then repeating this exercise. This helps to improve the blood flow to the peripheral tissues.

There are medical procedures as well. These may include a medication, called atorvastatin 80mg, clopidogrel 75mg once a day, or aspirin if these are unsuitable. Naftidrofuryl oxalate is a 5-HT2 antagonist which acts as a peripheral vaso-dilator and can therefore, improve blood flow to the peripheral tissues.

Surgical options include angioplasty and stenting, endarterectomy which involves cutting the artery open and removing the plague, and bypass surgery, which uses a graft to bypass a blockage. Endovascular angioplasty and stenting involves inserting a catheter through the arterial system, under X-ray guidance, then at the point of the stenosis, a balloon is inflated and space is created in the lumen of the vessel. This stent keeps the artery open. Endovascular procedures may have fewer risks but may not be suitable for more advanced disease.

Management of Critical Limb Ischemia

These individuals are given urgent referral to vascular specialists. They require analgesia to mange pain, urgent revascularization either by endovascular angioplasty or stenting, endarterectomy, or bypass surgery. Amputation may also be used to remove the limb if it is not possible to restore the blood supply.

Management of Acute Limb Ischemia

Remember that acute ischemia is rapid-onset, typically related to a thrombus blocking blood supply to a distal limb, similar to a thrombus blocking a coronary artery during a heart attack. Patients with acute limb ischemia need an urgent referral to the on-call vascular team for assessment and management. Options include endovascular thrombolysis, which involves inserting a catheter through the arterial system to apply thrombolysis directly into the clot, endovascular thrombectomy which involves inserting a catheter through the arterial system by removing the thrombosis through aspiration or mechanical devices, and surgical thrombectomy which involves cutting open the vessel and removing the thrombosis, endartectomy, bypass surgery, or amputation of the limb if it is not an option to restore the blood supply.